This is unlikely to happen. It makes more sense to ban cryptocurrencies themselves than centralized exchanges. Imagine a situation where the government saw a threat in food products and banned stores that sell those products. Why? Wouldn't it be easier to ban the food itself? With the level of legalization of cryptocurrencies and the acceptance of cryptocurrency in general, a move like a complete ban on exchanges would be extremely illogical. After all, if you ban exchanges, there will be other ways to sell cryptocurrencies, and decentralized exchanges can also be banned, because they also act under someone else's jurisdiction.

In simple words, banning centralized exchanges is slightly less stupid than banning bitcoin. There is already too much money involved in the industry and too much infrastructure built for governments to take such stupid steps.